It is known that a polymer having optical anisotropy is obtained by polymerizing a polymerizable compound when the compound has liquid crystallinity (patent reference No. 1). This is because the alignment of liquid crystal molecules is fixed by means of polymerization. A liquid crystal compound having —O—CO—CH═CH2 has been used as an example of such a compound (patent reference No. 2). A compound which is polymerizable in air on irradiation with ultraviolet radiation is also known (patent reference No. 3). Such a polymerizable liquid crystal compound can be copolymerized with a polymerizable compound having no liquid crystallinity. At this point, this non-liquid crystal compound plays a role in controlling characteristics of the resultant polymer. Thus, the development of a polymerizable non-liquid crystal compound is important in order to obtain a polymer having a suitable optical anisotropy.
An optical component composed of a polymerizable compound or a polymer having a spirobiindan-skeleton is known to have an excellent transparency, mechanical strength and heat resistance, and a low birefringence (patent reference Nos. 4 and 5). Polyester compounds having no polymerizable groups, which are derived from spirobiindans and benzoic acid or the like, are known to exhibit liquid crystal phases (non-patent reference No. 1). However, usefulness caused by the addition of these compounds to a liquid crystal composition has not been described.    Patent document No. 1: JP 2001-055573 A,    Patent document No. 2: JP 2001-154019 A,    Patent document No. 3: JP 2005-060373 A,    Patent document No. 4: JP H11-29526 A (1999),    Patent document No. 5: JP 2002-241348 A, and    Non-patent document No. 1: Kricheldorf, Hans R. et al, Journal of Polymer Science, Part A: Polymer Chemistry (1998), 36(9), 1387-1395.